We have continued our study of the two promoters in the gel operon. Both promoters are inducible by galactose, and operator constitutive mutants are found that allow expression of either or both in the absence of inducer. cAMP and its receptor protein are required to activate one promoter (PI) whereas they act to prevent expression of the other (PII). Expression of PI yields equal production of all three enzymes in the operon whereas expression of PII yields much greater expression of the promoter proximal gene. In our study of transcription termination by Rho factor, we have determined that termination in vivo and in vitro occur at identical sites on lambda (tr1). Rho recognizes RNA polymerase at these sites since both polymerase and Rho mutant proteins can interact in an allele specific way to affect the termination. We have also expanded our study of the pleiotropic defects of the rho mutations, the role of gene N of lambda in transcriptional anti-termination, and the effects of lambda gene expression on host cell physiology.